Package drying apparatus and method

ABSTRACT

Apparatus and method for drying the seal area ( 316 ) of a contact lens blister package ( 300 ) prior to affixing a lidstock to the seal area ( 316 ) includes a vacuum block ( 54 ) to which one or more vacuum heads ( 50 ) are removably mounted. The vacuum heads ( 50 ) include vacuum tips ( 52 ) which engage and circumscribe the seal area ( 316 ) removing moisture therefrom. Should a vacuum head ( 50 ) become damaged, it is quickly and easily replaceable upon the vacuum block ( 54 ).

The present invention relates to the manufacture and packaging of ophthalmic lenses, and more particularly relates to an apparatus and method for drying the seal area of a blister package immediately prior to sealing (e.g., by heat) a cover (also known as lidstock) to the seal area of the package.

Ophthalmic lenses such as contact lenses, for example, are typically packaged in a disposable plastic container known generally as a “blister package”. The blister package has a well in which the lens and a packaging solution are deposited. The packaging solution is necessary to keep the lens in a hydrated state during shipping and storage. A cover such as a foil lidstock is applied and heat sealed to the area surrounding the well. The user peels away the lidstock to access and remove the lens from the well (usually with a finger), at which time the blister package, solution and cover may be disposed of.

It is very important that the cover is securely sealed to the blister package so as to prevent leakage of solution from the blister package during shipping and storage thereof. Should solution leakage occur, the sterility and hydrated state of the lens is breached, thereby requiring rejection of the entire lens and blister package.

A typical molded, soft lens manufacturing environment incorporates the following basic process operations (not necessarily in this order):

a) Making of the female and male mold halves;

b) Depositing monomer into the female mold half;

c) Capping the male mold half onto the female mold half;

d) Curing the monomer;

e) Removing the male mold half from the female mold half;

f) Removing the lens from the mold;

g) Hydrating and extracting volatiles (if needed) from the molded lens (sometimes this is done directly in the lens package);

h) Depositing the lens into the well of a blister package (the blister package may be the male mold—see, e.g., U.S. Pat. No. 5,573,108);

i) Depositing a solution in the well with the lens; and

j) Applying a cover to the well to seal the lens and solution in the blister package.

The cover is thus applied to the blister package with the lens and solution located in the well thereof. The cover is typically a flexible lidstock (e.g., a foil) with printing thereon to identify the manufacturing lot and other lens information as desired. The lidstock is affixed to the blister package with a liquid-tight seal being made in about the entire periphery of the well to prevent leakage and preserve lens sterility as discussed above. One manner of affixing the lidstock to the blister package is with a heating element to cause a heat seal between the cover and blister package in the area surrounding the well, although other methods are also used in the art. The portion of the lidstock located outwardly of the seal area is typically left un-affixed to the blister package to permit easy peeling away of the lidstock from the blister package when opening the package to retrieve the lens. Since the lens is housed within the package well with a storage solution, the solution may wet the area surrounding the well where the lidstock is to be affixed. Needless to say, any moisture on the seal area will impede a secure seal between the lidstock and blister package which is highly undesirable as explained above. It is thus necessary to dry the seal area prior to affixing the lidstock thereto. This may be accomplished with a vacuum head that vacuums any moisture from the seal area such that the lidstock may be reliably affixed to a dry seal area. In a lens manufacturing process which is a batch process, an array of lens packages are typically processed simultaneously.

In a broad aspect, the invention comprises a vacuum block having an array of vacuum heads to dry a respective array of blister packages at the same time. The array of vacuum heads are aligned with respective packages of a like array of blister packages and are moved in a circular pattern to circumscribe the entire seal area which is at the periphery of the well. Each vacuum head circumscribes a respective blister package seal area removing any moisture therefrom and thereby providing a dry seal area for affixing the lidstock thereto. In a particularly advantageous aspect of the invention, the vacuum heads are individual components which are individually mounted and removable from the vacuum block. The vacuum block is bored to provide the vacuum channels to which the individual vacuum heads are interconnected. The vacuum heads themselves each include a longitudinal bore which aligns with the vacuum channels of the vacuum block when in the fully-inserted position. The provision of the vacuum heads being individually mounted and removable from the vacuum block allows for a damaged vacuum head to be quickly replaced on the vacuum block without requiring replacement of the entire vacuum block and without substantial down-time of the machine.

The present invention will be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of one embodiment of contact lens blister package;

FIG. 2 is a partial cross-sectional view of the blister package with a lidstock affixed thereto;

FIG. 3 is the view of FIG. 1 showing a lidstock affixed thereto;

FIG. 4 is another embodiment of contact lens blister package;

FIG. 5 is another embodiment of contact lens blister package;

FIG. 6 a is a fragmented, cross-sectional view of the vacuum block and vacuum head of the present invention;

FIG. 6 b is a fragmented, perspective view of the vacuum block and vacuum head engaging the seal area of a blister package in the intended manner; and,

FIG. 6 c is an end view of the vacuum tip.

Referring to the drawing, FIG. 1 shows an embodiment of one type of disposable plastic blister package used for packaging a contact lens. More specifically, as seen in FIG. 1, package 10 generally comprises support base 12 with concave recessed well area 14 for receiving and holding contact lens 5 therein. Generally, the contact lens will be packaged along with an aqueous storage fluid, such as buffered saline solution, in well area 14. Package 10 may be molded from a material such as polypropylene. Base 12 includes a substantially planar top surface 16 and a seal area 20 encircling the periphery of well area 14. Seal area 20 may be raised relative to the remainder of top surface 16 if desired. Also, while raised surface 20 is shown to be ring-shaped, other shapes are may be used, for example, a chevron-shaped raised surface surrounding the well.

FIG. 4 shows another embodiment of blister package 200 having a generally circular seal area 210 surrounding well area 212 in which a lens 214 is deposited with an aqueous storage solution 216. Seal area 210 requires drying prior to affixing the lidstock thereto to ensure a liquid-tight seal as stated above.

FIG. 5 shows yet another embodiment of blister package 300 which is actually the male mold half used in molding the lens 310 deposited in well area 312 with solution 314. Blister package 300 includes a seal area 316 surrounding well area 312 to which a lidstock 318 is affixed. Seal area 316 requires drying prior to affixing the lidstock thereto to ensure a liquid-tight seal as stated above.

While several embodiments of blister packages have been shown herein, it is understood that other package styles may be used and benefit from the advantages of the present invention which particularly provides a dry seal area for securely and reliably affixing a lidstock to the blister package.

As seen in FIG. 2, in the embodiment where seal area 20 is raised, outer wall 22 forms a substantially right degree angle with respect to raised surface 20. A contact lens 5 is been deposited in well area 14 with a quantity of aqueous storage solution 7. Lidstock 30 is applied, so as to cover substantially the entire top surface 16, for example by heat-sealing the lidstock about annular surface 20, and thereby hermetically sealing lens 5 in well 14 of package 10 (see also FIG. 3). It is noted that raised surface 20 is a generally flat annular surface as illustrated in FIG. 2. As such, moisture may collect on surface 20 (e.g., during solution fill) which, if not dried, would interfere with a proper seal of lidstock 30 thereto.

Referring now to FIGS. 6 a and 6 b, an embodiment of the invention is shown which is an apparatus useful for drying the seal area of a blister package prior to affixing a lidstock thereto. The invention includes one or more vacuum heads 50 which have a vacuum tip 52 at one end thereof and a vacuum channel V₁ extending longitudinally therethrough. Vacuum head 50 is mounted to a vacuum block 54 which includes one or more vacuum channels V₂ connected to a vacuum source Vs. The vacuum block 54 and vacuum heads 50 may be formed of any suitable material, one example being acetal. Vacuum block 54 is moved such that the vacuum head and more particularly, the vacuum tip 52, is moved into engagement with the seal area 316 of a respective package 300. With a vacuum applied, the vacuum block 54 is moved to cause the vacuum tip 52 to circumscribe the entire seal area, thereby removing any moisture therefrom. Once dry, the vacuum block 54 and vacuum heads 50 are moved away and the blister package is ready for the lidstock to be affixed thereto. In the preferred embodiment, the lidstock is affixed by the application of heat, although other affixing methods may be used if desired (e.g., with an adhesive). The seal between the lidstock and blister package is hermetic to prevent leakage of solution therefrom and also to prevent a breach of the sterility in the well area. The lidstock portions located outside the seal area may be left un-affixed so as to permit easy peeling of the lidstock from the package when opening the package for retrieval of the lens.

In high speed manufacturing processes, lenses are typically processed in batches and are placed in ordered arrays as they travel from one process station to another. As an example, an array of 15 lenses are arranged in a 3×5 array. It is understood, however, that the present invention is not limited to any particular number or array of lenses. In this type of array, the blister packages are held on a suitable support in the array. Once a lens and storage solution has been deposited into each of the blister packages in the array, the vacuum block and lens package array are placed in vertical alignment with the vacuum block located above the array. The vacuum block and array are moved toward one another until a respective vacuum tip comes into engagement with the seal area of a respective blister package. With the vacuum source activated, the vacuum tips are moved to circumscribe the entire seal area, thereby drawing off any moisture on the seal area. One full revolution of the vacuum tip about the seal area is usually sufficient to remove all the moisture from the seal area, although this step may be repeated if necessary. The vacuum block together with the vacuum heads are then cleared from the blister packages, at which time the array of blister packages are ready for affixing a lidstock thereto.

The vacuum heads of the present invention are made to be easily removable and replaceable upon the vacuum block. As such, should one or more of the vacuum tips become damaged, only the vacuum head(s) which is damaged needs to be removed and replaced upon the vacuum block. This saves time and money over a vacuum block which incorporates integral vacuum heads. In case where the vacuum heads are integrally formed with the vacuum block (e.g., by CNC machining), the entire vacuum block would require replacing, an expensive and time-consuming job.

Thus, as seen best in to FIG. 6 a, vacuum head 50 is a separate piece which is mounted to the vacuum block 54 by a screw 55 which is secured into the end of vacuum head 50 located opposite vacuum tip 52. An annular locating flange 57 is formed adjacent vacuum tip 52 to secure vacuum head 50 within a respective vacuum head bore 59 formed in vacuum block 56. A pair of rubber O-rings 61 a, 61 b are attached about vacuum head 50 both above and below vacuum channel V₁ to ensure a good vacuum seal. When using an array manufacturing format, the vacuum head bores are formed in vacuum block 56 in the same spacing and array as the blister packages are presented to the vacuum block so that proper alignment between the vacuum heads 50 and blister packages is maintained.

In the preferred embodiment, as shown in FIG. 6 c, each vacuum tip 52 includes castellations formed by two perpendicular slots S₁ and S₂ which are provided to draw an effective drying vacuum when the vacuum tip is engaged with and is circumscribing the seal area of a respective blister package. The castellations are prone to damage as compared to other portions of the vacuum head. By providing vacuum heads which are individually removable and replaceable upon vacuum block 56, the damaged vacuum heads 50 may be quickly and easily replaced on vacuum block 56. 

1. Apparatus for vacuum drying the seal area of a blister package prior to affixing a lidstock to the seal area, the apparatus comprising: a) a vacuum block having one or more vacuum channels extending therethrough for communication with a vacuum source; b) at least one vacuum head having a vacuum tip at one end thereof, the vacuum head and tip having a vacuum channel extending longitudinally therethrough, and being removably mounted to the vacuum block with the vacuum channel of the vacuum head communicating with the vacuum channel of the vacuum block whereby upon activation of the vacuum source, a vacuum is drawn at the vacuum tip, whereby the vacuum tip may be engaged with the seal area of a blister package with the vacuum removing moisture from the seal area prior to affixing a lidstock to the seal area.
 2. The apparatus of claim 1, including a plurality of vacuum heads mounted in the vacuum block whereby a like plurality of blister packages and respective seal areas may be engaged by the plurality of vacuum tips, respectively, and be dried thereby.
 3. The apparatus of claim 1 or claim 2 wherein the or each vacuum head includes a castellation formed by first and second slots extending perpendicular to each other at a respective vacuum tip.
 4. The apparatus of any one of the preceding claims, wherein the or each vacuum head is removably mounted to the vacuum block by a screw extending through the vacuum block and threaded into the end of a respective vacuum head opposite the vacuum tip.
 5. The apparatus of any one of the preceding claims wherein the or each vacuum head is formed of acetal.
 6. A method for vacuum drying the seal area of a blister package prior to affixing a lidstock to the seal area, the method comprising the steps of: a) providing a vacuum block having one or more vacuum channels extending therethrough for communication with a vacuum source; b) providing at least one vacuum head having a vacuum tip at one end thereof, the vacuum tip having a vacuum channel extending longitudinally therethrough, the vacuum head being removably mounted to the vacuum block with the vacuum channel of the vacuum head communicating with the vacuum channel of the vacuum block whereby upon activation of the vacuum source, a vacuum is drawn at the vacuum tip; c) engaging and circumscribing said vacuum tip with the seal area of a blister package with the vacuum at the vacuum tip removing moisture from the seal area; and d) affixing a lidstock to the seal area.
 7. An apparatus substantially as shown in or as described with respect to any of the accompanying drawings.
 8. A method of vacuum drying the seal area of a blister pack substantially as described with respect to any of the accompanying drawings. 